This invention relates to a surgical knot made from a suture filament. In particular, the invention relates to a partially tied surgical knot which is particularly adapted for deployment into a fully tied knot during minimally invasive surgical procedures where access to the surgical site is limited.
A mainstay of surgical practice has been and will continue to be the formation and placement of surgical knots from suture filament to fasten tissue during an operative procedure. Numerous surgical knots have been developed over an appreciable period of time, and the art of forming and tying knots for surgical applications is a critical skill which a surgeon must possess to perform an operation safely and efficiently. Accordingly, the art is extensively developed. See, for example, Tissue Approximation in Endoscopic Surgery, Alfred Cuschieri, Zoltan Szabo, Times Mirror International Publishers, 1995, which describes numerous surgical knots made from suture filament to facilitate the approximation of tissue during surgery.
The art of surgical knots is also well represented in the patent literature. U.S. Pat. No. 2,012,776 discloses a surgical instrument for facilitating the placement of various forms of slip knots made from surgical filament. The inventor named on the '776 patent, H. A. Roeder, developed the "Roeder Knot" which is a surgical knot which is frequently used in practice today. More recently, U.S. Pat. No. 5,573,286 discloses a surgical knot of suture strand particularly adapted for orthopedic applications. The preferred embodiment described in the '286 patent is directed to tying the knot to a bone.
Early on, it was recognized that the deployment and placement of surgical knots within a remotely accessible surgical site could be difficult, cumbersome and often unreliable. Accordingly, instrumentation was developed to facilitate the placement of knots in remote locations. Cleverly, a pre-tied knotted loop of suture was often used to reduce the number of steps required to form the tightened knot. For example, U.S. Pat. Nos. 2,566,625 and 3,090,386 describe surgical devices which are adapted to support a pre-tied knotted loop of suture for suturing or ligating tissue, particularly during procedures where the tissue desired to be manipulated is difficult to access.
More recently, instrumentation has been developed for facilitating the placement of knots particularly during minimally invasive surgical procedures. In particular, U.S. Pat. No. 5,320,629 discloses the formation of a pre-tied knotted loop of suture, and the placement of the pre-tied knotted loop on a surgical device for facilitating the tightening of the loop to approximate tissue during endoscopic surgical procedures. German Patent No. 912619 also discloses a device similar to that disclosed in the '629 patent.
Although the art of surgical knots is well developed, and surgical devices for facilitating the placement of fully tightened knots from a pre-tied knotted loop of suture have also been developed for application at remote surgical sites, there are problems which still need to be addressed. In particular, in those surgical procedures where access to the site is limited, for example during minimally invasive procedures such as endoscopic surgical procedures, the knots which are deployed are routinely slip knots which have poor knot security. If knot security is poor, then the approximated tissue may not be held for a sufficient period of time to promote adequate wound healing. Additionally, during minimally invasive procedures, the pre-tied knotted loops of suture which have been described in the prior art devices can be difficult to efficiently tighten for final deployment.
Therefore, in minimally invasive surgical procedures where access to the surgical site is limited, what is needed is a partially tied surgical knot formed from a suture strand which will yield enhanced suture knot security when the knot is fully formed. The partially tied knot should be relatively simple in construction. It should be easy to form the tightened knot from the partially tied knot, which characteristically is in the form of a pre-tied knotted loop of suture. The formation of the knot from the pre-tied knotted loop of suture should provide a consistently strong knot security each time the knot is placed to enable even an inexperienced surgeon to confidently and efficiently place a secure suture knot. Additionally, the surgical knot should not only have enhanced suture knot security when formed, but also long term security to maintain tissue in its approximated state for a sufficient period of time to promote adequate wound healing. Finally, it would be ideal if the amount of tension which must be applied to the suture strand when the pre-tied knotted loop of suture is tightened is kept sufficiently low so that the suture does not break when the knot is deployed.